The present invention relates to a method for wrapping of an article such as a bundle of lumber, plywood or chipboard, or a pile of other articles, for instance, articles used in construction work, or a paper or pulp bale or a similar essentially parallepipedly shaped article. The invention relates further to an apparatus realizing the inventive method.
It is prior known to wrap or envelop articles having an essentially orthogonal form, such as bundles of lumber, pulp or similar, from the five sides thereof by suitable wrapping material. In most cases this is done to protect the articles, for instance to give a protection to them during the transportation and storage. In addition, the wrapper sheet provides a solid surface for various marking, identifiers and labels or even for commercial advertisements. The wrapper may also be used to give the articles a neater appearance, and to hide some details of the wrapped material which are not intended to be seen by the public.
The placement and folding of the wrapper sheet is usually a manual or semi-automatic operation, whereby a web like wrapper material has been supplied from a material roll positioned above the article to be wrapped. The article might be placed on a conveyor, and the wrapper is drawn from the roll on top of the article as the article passes by the roll. As the rear end of the article has passed the material roll, the material web is cut by manual or semi-automatic means. Then the wrapper material is folded manually i.e. by hand around the article. The attachment of the wrapper foldings or tongues, which may be effected by gluing, taping, riveting, and the other possible stages, such as stages for setting various plastic or steel bands around the package has been correspondingly performed manually.
There are several disadvantages with the prior art wrapping arrangements. The level of automation of the prior known methods and apparatus is low, and thus several workers are required when folding and attaching the wrapper. Known wrapping arrangements are labor intensive and time-consuming to operate. Due to an excessive amount of manual handling, the quality and especially the uniformity of the packages has not met today's requirements. Furthermore, when wrapping by the present methods, it is usual that the wrapper sheet fails to become wound sufficiently tightly around the article and against the surfaces thereof, and is thus very easily ripped, for instance by an air flow penetrating between the article and the wrapper during transportation. In addition, the appearance of the manually made wrappers has not always been satisfactory. When some other means than adhesive or similar means, such as steel band or steel rivets or nails, has been used to attach the wrapper, they have caused harm and disadvantages during the further processing of the wrapped articles, for instance when sawing or chipping of deal planks or boards.
Finnish Patent Application No. 923272 discloses a method and apparatus by means of which paper pulp bales are wrapped by folding and subsequent gluing of a wrapper sheet. More precisely, said application discloses an apparatus which can be used only when essentially short parallelepiped bales, i.e. essentially cubically shaped pulp bales are wrapped. Said apparatus comprises means for folding the wrapper in the end surfaces of the bale and means for applying adhesive to the folded tongues of the wrapper prior pressing them towards the ends of the bale.
In practice, however, such paper pulp bale wrapper includes several disadvantages. The proposed apparatus folds the wrapper only in the ends of the bale, and thus the sides thereof need to be folded outside of said apparatus. Furthermore, said apparatus is constructed to bales having essentially equal dimensions, and thus can be utilized only with articles having dimensions corresponding to the set values. In addition, the apparatus according to FI application 923272 cannot be suited for articles being essentially longer than the width and height thereof is.
Therefore, it is an object of the present invention to overcome the disadvantages of the prior art arrangements and to provide a totally new type of solution for the wrapping of articles, especially articles having an essentially parallelepiped shape. The solution according to the present invention provides a simple, reliable and automatic manner for the wrapping.
Another object of the present invention is to provide a method and apparatus by means of which the wrapping of articles can be performed as a continuous process.
Still another object of the present invention is to provide a method and an automatic wrapping apparatus, by which articles having essentially different widths and/or lengths and/or heights can be wrapped.
It is also an object of the present invention to provide a wrapping device and a method in which a suitable web-like wrapper material, such as paper, board or plastic sheet is drawn from a suitable source of material, such as from a wrapper material roll, the width of said web-like material being adapted to be modified according to the dimensions of the article to be wrapped in the beginning or during the wrapping procedure.
A still further object of the present invention is to provide a method and a high-speed wrapping apparatus by means of which it is possible to provide wrappers having an uniform appearance and being tight enough to withstand the stresses caused by various handlings, such as transportation and storage.
A still further object of the present invention is to provide a method and apparatus by which even such articles, which comprise essentially irregular surfaces, and/or which comprise extensions and/or concaves in the surfaces thereof, and/or which comprise inclined surfaces, can be provided with a wrapper having an essentially uniform and trimmed appearance.
Other objects and advantages of the present invention will be brought out in the following part of the specification taken in conjunction with the accompanying drawings.